HowTo: Scrollable wheel?

Hello,

Whats the best way to achieve a scrollable wheel such as

http://www.musicwheels.com/images/musicwheels_scales_only.swf

I would like to produce something similar where by the various wheels can be rotated individually around the common centre.

Notice the movie clip also snaps to the exact position when released. How is this achieved?

Regards,

Steven Jenkins